how to set downloaded firefox to default web browser in debian?

view story

http://unix.stackexchange.com – i downloaded firefox to home dir and extract there. Now how i can set this firefox to default web browser that when I click a link in another application open link in this firefox? i uses this command but doesn't work: update-alternatives --install /usr/bin/x-www-browser x-www-browser /home/user/firefox/firefox 100 and this: update-alternatives --set x-www-browser /home/user/firefox/firefox what can i do? (HowTos)